The present invention relates to a process for the production of a transverse thrust in a flying object in which a defined quantity of a monergol propellent substance is introduced into a propulsion unit, which is arranged transversely relative to the longitudinal axis of the flying object, together with a supersonic nozzle and the monergol substance is combusted by means of a source of heat in order to produce the desired thrust for a prescribed time.
Such a process serves, in particular, for correcting the position and path of flying objects during space travel; in this connection, one or more propulsion units can be provided which are arranged transversely relative to the longitudinal axis of the flying object and which are ignited individually at prescribed points in time in order to be able to carry out the desired path correction.
Solid propulsion units are often used for path correction, whereby one propulsion unit is required for each of the correction impulses, which are to be imparted repeatedly, so that a number of solid propulsion units have to be provided in the flying object with a correspondingly large mass and correspondingly large incorporated volumes. In order to carry out the actual control of the transverse thrust, the gas stream has to be controlled by hot gas valves and this requires expensive actuation devices.
A propulsion unit for the path correction of flying objects during space travel is known from EP-A 522,270, which comprises a housing, which is constructed as an anode and forms the expansion nozzle, and a rod-shaped, electrically insulating cathode which is held centrally therein. The cathode is arranged in a combustion chamber into which the propellent gases are injected, the tip of the cathode being separated from the narrow cross section of the throat of the nozzle via a small air gap. An arc is ignited between the anode and the cathode when gas is flowing through and the propellent gases are able to absorb additional thermal energy from the arc. A portion of the propellent gas is injected into the combustion chamber via a central hole which is arranged in the cathode. The cathode tip, which is located opposite the throat of the nozzle, is formed from an insert comprising tungsten. The propellent gas is generally a mixture comprising a ammonia, nitrogen gas and hydrogen gas and is produced by the thermal and/or catalytic decomposition of hydrazine (N2 N4) and initially has a temperature of the order of 500 to 600xc2x0 C. upon its entry into the combustion chamber and is heated to temperatures of 10,000 to 14,000xc2x0 C. in the arc before it leaves the expansion nozzle and produces the desired transverse thrust.
Because of the concentration of the arc stream in a comparatively narrow region, especially in the region of the cathode tip, such a propulsion unit is thermal stressed to an extraordinarily intense degree, especially in the region of the cathode. This adversely affects the working life of such a propulsion unit.
The use of monergols, e.g. hydrazine, as a propellent substance for a flying object, especially a satellite, is known from DE-A 2,537,543. In this connection, the term monergol is to be understood to mean a liquid propellent substance which generates a gas via decomposition as a result of its intrinsic conversion, without the addition of any further substance, due to an appropriate energy input, whereby this gas can be used to subject the propellent substance to pressure.
The use of a pyrotechnic gas generator for the purpose of steering flying objects or end-phase guided missiles is known from DE-A 3,616,184, in which a propellent charge is converted to gas in a combustion chamber and this gas is fed to control nozzles when a steering correction is required. The mode of operation of this known gas generator which is usable for control purposes is possible within the combustion chamber only under conditions of constant pressure, so that excess pressure peaks are to be avoided in particular. This can be achieved by means of mechanical excess-pressure valves which essentially comprise a spring/mass system and which consume a large amount of space so that they can no longer be arranged in the immediate vicinity of the combustion chamber, especially in end-phase guided missiles. In addition, mechanical excess-pressure valves exhibit poor response characteristics because of the relatively large time constants of the spring/mass system and these do not meet the requirements that are required in practice. Moreover, the opening and closing characteristics of conventional mechanical excess-pressure valves are associated with excessively large tolerances which exclude their use in precision steering arrangements. In order to avoid these disadvantages, this reference provides a pressure sensor in the combustion chamber which is connected to an electronic circuit on the outlet side in order to determine the specification pressure, which depends on the temperature and the prescribed combustion velocity of the propellent composition, and a temperature sensor of the propulsion composition which is connected to the electronic circuit, along with an adjusting element which opens the combustion chamber to dissipate the pressure peak in the event of sensing a pressure in the combustion chamber which exceeds the specification pressure.
The main object of the present invention is to provide an especially simple and rapidly responding process for the production of a transverse thrust in a flying object, in which a thrust of high impulse force can be produced by the process in a short time and in a defined direction.
In accordance with the above and further objects, the invention provides a process for the production of a transverse thrust in a flying object in which a defined quantity of a monergol propellent substance is introduced into a propulsion unit, which is arranged transversely relative to a longitudinal axis of the flying object to produce a thrust transverse to said longitudinal axis of the flying object, the propulsion unit having a combustion chamber, a supersonic nozzle connected to the combustion chamber and a source of heat to combust the propellant and produce the desired thrust for a prescribed time. The process comprises the steps of introducing a monergol propellent substance tangentially into an inlet in the combustion chamber to form a film of the propellent substance on an inside surface of a wall of the combustion chamber. Combustion of the film of propellent substance on said wall is effected by a pyrotechnic source of heat which is arranged in said wall of the combustion chamber in the vicinity of a throat of the supersonic nozzle. Hot gases produced by the combustion of the propellant substance produce a high pressure of 500 to 800 bars in the combustion chamber, and produce said transverse thrust in the supersonic nozzle. In accordance with the process the propellent substance is supplied to the combustion chamber through an inlet line extending tangentially to said combustion chamber and supply of the propellent substance to the combustion chamber is obtained by a valve. The high pressure in the combustion chamber is prevented from reaching said valve by connecting an outlet line from the combustion chamber to said inlet line at a location between said valve and said inlet of the combustion chamber, said outlet line being joined to the inlet line to merge therewith at a relatively small angle so as to be substantially parallel thereto. In this way, the pressure component of the combusted monergol at the connection of the outlet line to the inlet line can substantially equalize the pressure at the inlet of the combustion chamber and thus serve as a non-return valve which prevents the high pressure in the combustion chamber from reaching the inlet valve.